Answer: A. Active
Explanation: In this sentence, "rain" (the subject) performs the action of falling, making it an active voice sentence.
The verb "fell" connects the subject "rain" to the action, showing an active construction.
Active voice statements are usually more straightforward and clear than passive voice sentences. In this line, the rain is explicitly identified as the performer of the action. According to the one who is doing the action and the sentence structure, "Rain fell constantly for three days" is in the active voice.
